Adjustable height support

ABSTRACT

An adjustable height support for furniture and the like features a ball wedge positive lock between the two relatively linearly movable units of the support structure. A retarder or drag device between the relatively movable units is activated in the locking engagement preliminary to the positive engagement of the ball wedge lock. Height adjustment is infinite so as to increments of adjustment and locking is substantially instantaneous.

United States Patent Snurr 1 1 June 5, 1973 [54] ADJUSTABLE HEIGHTSUPPORT [76] Gordon R. Snurr, 520 W. 6th

Street, Waynesboro, Pa. 17268 Filed: Mar. 29, 1972 Appl. No.: 239,035

Inventor:

52 US. Cl. ..248/412, 108/144, 287/58 CT, 297/345 Int. Cl ..E04g 25/08Field of Search ..248/410, 411, 412, 248/414,125,188.5, 295, 336, 337;287/58 [56] References Cited UNITED STATES PATENTS Junkunc ..287/58 CTDaws0n....

Lief ..248/412 2,961,260 11/1960 Newlin ..287/58 CT 3,480,247 11/1969Waner ..248/336 FOREIGN PATENTS OR APPLICATIONS 8/1926 Great Britain..248/412 Primary Examiner-Marion Parson, Jr. Attorney-Brady, OBoyle &Gates [5 7] ABSTRACT An adjustable height support for furniture and thelike features a ball wedge positive lock between the two relativelylinearly movable units of the support structure. A retarder or dragdevice between the relatively movable units is activated in the lockingengagement preliminary to the positive engagement of the ball wedgelock. Height adjustment is infinite so as to in-' crements of adjustmentand locking is substantially instantaneous.

11 Claims, 6 Drawing Figures ADJUSTABLE HEIGHT SUPPORT The object of theinvention is to provide an improved, simplified, reliable and safeheight adjustment mechanism for furniture legs, stool and tablepedestals, drafting boards and the like. More particularly, the aim ofthe invention is to provide an adjustable height support which isoperable quickly without the use of handles, levers, screws or otherrelease devices. In accordance with the invention, the user of a stoolor the like equipped with the invention may adjust the stool to anydesired height and securely lock it in the selected adjusted position bya simple lifting and release operation and without the aid of anyseparate or attached manual operators.

The invention is characterized by its extreme simplicity of constructionand operation, minimum number of parts and the avoidance of thenecessity for close manufacturing tolerances of fabricated parts, thusrendering the device economical to manufacture. The safety andreliability of the mechanism allows it to comply with all recent Stateand Federal industrial safety regulations.

While the invention is applicable to a wide variety of height adjustablestructures, it is thought to be particularly suitable for use withstools for technicians, dentists and the like, which must be frequentlyand quickly adjusted by the technician or dentist without distractinghim from his primary work.

Various features and advantages of the invention will become moreapparent during the course of the following detailed description.

BRIEF DESCRIPTION OF DRAWING FIGURES FIG. 1 is a central verticalsection through an adjustable height stool embodying the invention withthe locking mechanism shown in the active or locking positron.

FIG. 1A is an enlarged fragmentary vertical section through the ballwedge locking mechanism of the support in the active position.

FIG. 2 is a similar view showing the mechanism in the inactive orrelease position to allow raising and lowering of the stool.

FIG. 3 is a horizontal section taken on line 3-3 of FIG. 1A.

FIG. 4 is a similar section taken on line 44 of FIG. 1A.

FIG. 5 is a similar section taken on line 55 of FIG. 1A.

DETAILED DESCRIPTION Referring to the drawings in detail wherein likenumerals designate like parts, the numerals and 11 designate adjustabletelescopic assemblies or main units of an adjustable height stoolembodying the invention. It will become apparent that the stool may beraised and lowered and safely locked at any elevation within theavailable range of adjustment by a mere linear relative movement of theunits 10 and 11, initiated by simply relieving the locking mechanism ofthe weight of the assembly 11, followed by the quick release or droppingof this assembly. The resulting locking action, after height adjustment,is practically instantaneous. It should be pointed out prior toproceeding with the description that while the invention is beingdescribed in relation to a stool the structure is equally applicable tofurniture legs or pedestals, drafting boards, and a variety of similarstructures which require frequent and secure height adjustment.

Continuing to refer to the drawings, the assemblyor unit 10 comprises anupright cylindrical tube 12 having a sturdy disc 13 welded securely inits lower end. Any form of stable base 14 is rigidly secured to thelower end portion of the tube 12 to support the same vertically. Acentral vertical cylindrical post or shaft 15 has its lower end weldedwithin an opening in the disc 13 and extends axially through the tube 12and above the top end thereof, concentrically therewith. The top end ofthe shaft 15 carries a preferably plastic cylindrical head or disc 16,rigid therewith, serving as a guide element for the relatively movableunit 11 and also forming an upper and lower limit stop for theextensible unit 11. It may now be seen that the assembly or unit 10constitutes a base unit for the stool consisting of the above describedparts which are in fixed relation.

The relatively movable unit or assembly 11 comprises a cylindricalvertical tube 17 of somewhat smaller outside diameter than the bore oftube 12 and fitting telescopically into the latter. The bore 18 of tube17 receives the bearing element 16 slidably and a preferably plasticsleeve bearing 19 in the upper end of tube 12 receives the periphery ofthe tube 17 slidably. Therefore, the interior tube 17 is guided andsupported relative to the outer tube 12 at two axially spaced points bythe bearings 16 and 19 and this assures smooth axial relative movementbetween the units 10 and 11 when a height adjustment is being made.

The unit 11 further comprises a relatively heavy sleeve 20 or lockingbody fixedly secured in a slightly increased diameter lower end boreportion 21 of the tube 17. The body 20 has a relatively shortcylindrical bore 22 at its upper end surrounding the shaft 15 in spacedconcentric relationship. The bore 22 leads to a central steeply upwardlycylindrically tapered bore portion 23 in the locking body 20, in turnleading downwardly and joining an enlarged cylindrical bore portion 24which opens through the lower end of the locking body 20.

An annular group of wedge locking steel balls 25 surround thecylindrical steel shaft 15 within the confines of the tapered bore 23and these balls rest upon the annular upper end face 26 of a ballretainer and actuator sleeve 27. The retainer and actuator sleeve 27 hasa center cylindrical bore 28 surrounding the shaft 15 concentrically andspaced slightly therefrom. The top end of the sleeve 27 is externallytapered at 29 to prevent any interference between the sleeve and theconically tapered bore 23. The sleeve 27 has a free sliding fit on theshaft 15 and has its lower end 30 machined on an angle diagonally of theaxis of shaft 15 for a reason soon to become apparent. The sleeve 27also is freely slidable in the cylindrical bore portion 24 of lockingbody 20.

A drag or retarding ring 31 is disposed below the ball retainer andactuator sleeve 27 and has a central circular opening 32 of somewhatlarger diameter than the shaft 15 and loosely receiving the shaft. Theopposite ends of the bore or opening 32 form substantially squarecorners with the opposite faces of the ring 31.

The ring 31 is supported in spaced relation to the bottom of the tube 17and locking body 20 by a pair of vertically adjustable screws 33 and 34which project through openings in the drag ring and enter threadedopenings 35 in the lower end of the body 20. A light compression spring36 surrounds the screw 34 with its opposite ends bearing on one side ofthe ring 31 and the adjacent bottom face of the body 20. By means of thescrew 34, the tension of the spring may be adjusted and the height aswell as the angularity of the drag ring 30 may also be adjusted bymanipulating the screws 33 and 34 to provide a precise operation of themechanism. It may be seen that the top of the ring 31 contacts only thelowermost point of the sleeve 27, the weight or force transmittedthrough this freely sliding sleeve tending to cock or cant the drag ringin conjunction with the action of the spring 36.

In order to prevent relative rotationxbetween the sleeve 27 and thelocking body 20, a rigid key 37 on the locking body projects into akeyway 38 formed in the exterior of the sleeve 27 and extendinglongitudinally thereof. The sleeve 27 is freely movable longitudinallyand is not restricted in this movement by the .key.

While relative rotation between the units and 11 is possible mainlybecause the balls 25 are not positively wedged into contact with oneanother but only with the shaft 15 and bore portion 23, this rotation isnot relied upon in the case of a stool, and the seat 39 of the stool ispreferably interconnected with the top of tube 17 by a low frictionbearing 40.

The mode of operation of the adjustable height support is as follows:

When it is desired to raise or lower the seat 39 to any desired level,it is merely necessary for the user to slightly lift the seat and theunit 11 of which the seat is a part. As soon as the weight of the unit11 is held in the hands of the operator, the locking mechanism willassume the free or unlocked position shown particularly in FIG. 2 of thedrawings. At this time, the wedge locking balls 25 have dropped fromcontact with the tapered bore 23 and there is no longer any lock betweenthe units l0 and 11. Additionally, the canted drag ring 31 under theweight of sleeve 27 and the influence of spring 36 is now released fromgripping engagement with the shaft 15 and is resting upon the heads ofthe two screws 33 and 34 in a release position. The operator can nowraise or lower the seat 39 to any elevation limited only by the upperstop element 16 and the full down position of the unit 11.

When the desired height adjustment has been made, the operator merelyreleases and drops the seat unit 11 and when this is done the mechanismmoves substantially instantly to the positive locking position shown inFIGS. 1 and 1A. As the unit 11 is released and dropped for rapiddownward movement, the balls 25 and sleeve 27 will tend to drop but thepressure of spring 36 on the drag ring 31 plus the tendency for themassive locking body and tube 17 to move downwardly more rapidly thanthe sleeve 27 and balls will cause further canting or tilting of thering 31 which immediately grips the shaft 15 with adragging or retardingaction, FIG. 1A. This drag effect is sufficient to stop the downwardmovement of the sleeve 27 with the unit 11 and the stopping of thesleeve forces the balls upwardly into wedged locking engagement with theshaft 15 so that no further downward movement of the unit 11 ispossible. All of this action occurs almost instantly, as stated, whenthe unit 11 is dropped, so that the stool may be quickly andconveniently adjusted to any height.

More weight that is applied to the seat 39 after any given adjustmentthe tighter the wedging locking action becomes and therefore themechanism is completely safe and always reliable. Due to the steepnessof the tapered bore 23, the locking mechanism will always release easilywhen the weight of the unit 11 is transferred to the hands regardless ofthe amount of weight and the degree of shocks applied downwardly to thesupport. The free rolling action of the wedge locking balls also assuresunfailing release of the mechanism.

It must be fully understood in connection with the invention that thecanted ring 31 serves only as a drag or brake to retard the downwardmovement of the sleeve 27, preliminary to the wedge locking action ofthe balls relative to the shaft 15. In no case is the action of the ring31 relied upon to lock the support or to bear heavy weight, as thiswould be dangerous. instead, when weight is applied to the support, thisis resisted and supported by the wedged balls and the drag ring servesonly to initiate the locking action of the balls in conjunction with thefree sliding retainer and actuator sleeve 27. i

The terms and expressions which have been employed herein are used asterms of description and not of limitation, and there is no intention,in the use of such terms and expressions, of excluding any equiva lentsof the features shown and described or portions thereof but it isrecognized that various modifications are possible within the scope ofthe invention claimed.

1 claim:

1. An adjustable height support comprising a supporting base unitincluding a central upstanding shaft, a second unit connectedtelescopically to the base unit and adapted to be raised and loweredrelative to the base unit by axial movement, a gravity-responsive wedgelocking means on the second unit movable therewith and also movablerelative thereto, and said wedge locking means including a drag elementadapted to grip said shaft and initiate the locking action of the wedgelocking means when the second unit is abruptly released to a freefalling condition following height adjustment of the support, lifting ofthe second unit serving automatically to release the wedge locking meansand drag element.

2. The structure of claim 1, and the wedge locking means comprising onthe second unit a freely axially movable wedge device surrounding saidshaft, a cooperating tapered wedge bore on the second unit lockinglyengaged by the wedge device when the wedge device moves axially in onedirection on the second unit and forcing the wedge device into positivelocking engagement with said shaft, said drag element comprising acanted drag ring mounted loosely on said shaft and contacting the lowerend of said wedge device, and supporting and adjusting means for saidcanted drag ring on said second unit and allowing the inclination of thedrag ring to be varied and positively limiting downward displacement ofthe drag ring on the second 'unit re sponsive to lifting the secondunit.

3. The structure of claim 2, and said supporting and adjusting meanscomprising a pair of diametrically opposed adjusting screws on the lowerend of the second unit having heads supporting opposite sides of thedrag ring at different elevations, and a compression spring on oneadjusting screw having opposite ends engaging the top of the drag ringand the bottom face of the second unit.

4. The structure of claim 2, and said freely axially movable wedgedevice comprising an annular array of wedge locking balls in saidtapered wedge bore surrounding said shaft, and a ball retainer andactuator sleeve arranged below said balls and tapered bore andsurrounding said shaft and supporting said balls and having its lowerend contacting the top of the canted drag ring.

5. The structure of claim 4, and said sleeve having a diagonallyinclined lower end face and the lowermost part of said end face restingon the lower side of the canted drag ring.

6. The structure of claim 5, and said second unit having a lower endcylindrical bore below the tapered wedge bore receiving said sleeve forguided axial movement therein.

7. The structure of claim 5, and a key means on the second unit engagingsaid sleeve and resisting rotation thereof relative to the second unitwhile allowing free relative axial movement of the sleeve.

8. The structure of claim 1, and the second unit including a verticaltube body telescoped over said upstanding shaft of the base unit, and atleast one bearing element on the upstanding shaft slidably supportingthe bore of the tube body of the second unit.

9. The structure of claim 8, and said bearing element comprising abearing head secured to the upper end of said shaft.

10. The structure of claim 8, and said wedge locking means bodilycarried by the lower end of said tube.

body in surrounding relationship to said upstanding shaft.

1 1. The structure of claim 10, and said wedge locking means on thelower end of the tube body comprising a sleeve member having an internalupwardly tapering steep conical bore, said bore surrounding said shaftconcentrically, a freely axially movable sleeve surrounding said shaftbelow said conical bore, an array of wedge locking balls surroundingsaid shaft and resting on the top of said sleeve and disposed withinsaid conical bore, and an adjustable friction drag element dependinglysecured to the bottom of said sleeve member and adapted to engage saidshaft grippingly for forming a support for said frkeely movable :leeve.

1. An adjustable height support comprising a supporting base unitincluding a central upstanding shaft, a second unit connectedtelescopically to the base unit and adapted to be raised and loweredrelative to the base unit by axial movement, a gravity-responsive wedgelocking means on the second unit movable therewith and also movablerelative thereto, and said wedge locking means including a drag elementadapted to grip said shaft and initiate the locking action of the wedgelocking means when the second unit is abruptly released to a freefalling condition following height adjustment of the support, lifting ofthe second unit serving automatically to release the wedge locking meansand drag element.
 2. The structure of claim 1, and the wedge lockingmeans comprising on the second unit a freely axially movable wedgedevice surrounding said shaft, a cooperating tapered wedge bore on thesecond unit lockingly engaged by the wedge device when the wedge devicemoves axially in one direction on the second unit and forcing the wedgedevice into positive locking engagement with said shaft, said dragelement comprising a canted drag ring mounted loosely on said shaft andcontacting the lower end of said wedge device, and supporting andadjusting means for said canted drag ring on said second unit andallowing the inclination of the drag ring to be varied and positivelylimiting downward displacement of the drag ring on the second unitresponsive to lifting the second unit.
 3. The structure of claim 2, andsaid supporting and adjusting means comprising a pair of diametricallyopposed adjusting screws on the lower end of the second unit havingheads supporting opposite sides of the drag ring at differentelevations, and a compression spring on one adjusting screw havingopposite ends engaging the top of the drag ring and the bottom face ofthe second unit.
 4. The structure of claim 2, and said freely axiallymovable wedge device comprising an annular array of wedge locking ballsin said tapered wedge bore surrounding said shaft, and a ball retainerand actuator sleeve arranged below said balls and tapered bore andsurrounding said shaft and supporting said balls and having its lowerend contacting the top of the canted drag ring.
 5. The structure ofclaim 4, and said sleeve having a diagonally inclined lower end face andthe lowermost part of said end face resting on the lower side of thecanted drag ring.
 6. The structure of claim 5, and said second unithaving a lower end cylindrical bore below the tapered wedge borereceiving said sleeve for guided axial movement therein.
 7. Thestructure of claim 5, and a key means on the second unit engaging saidsleeve and resisting rotation thereof relative to the second unit whileallowing free relative axial movement of the sleeve.
 8. The structure ofclaim 1, and the second unit including a vertical tube body telescopedover said upstanding shaft of the base unit, and at least one bearingelement on the upstanding shaft slidably supporting the bore of the tubebody of the second unit.
 9. The structure of claim 8, and said bearingelement comprising a bearing head secured to the upper end of saidshaft.
 10. The structure of claim 8, and said wedge locking means bodilycarried by the lower end of said tube body in surrounding relationshipto said upstanding shaft.
 11. The structure of claim 10, and said wedgelocking means on the lower end of the tube body comprising a sleevemember having an internal upwardly tapering steep conical bore, saidbore surrounding said shaft concentrically, a freely axially movablesleeve surrounding said shaft below said conical bore, an array of wedgelocking balls surrounding said shaft and resting on the top of saidsleeve and disposed within said conical bore, and an adjustable frictiondrag element dependingly secured to the bottom of said sleeve member andadapted to engage said shaft grippingly for forming a support for saidfreely movable sleeve.